Absorption refrigerating machine

ABSTRACT

To provide a highly efficient and compact absorption refrigerating machine with water heated from 60 to 70 degrees Celsius as the heat source. In an absorption refrigerating machine including a regenerator G, condenser C, an absorber A, an evaporator E, an auxiliary regenerator GX and an auxiliary absorber AX, the concentrated solution from G is heated and further concentrated in GX, while the diluted solution from A is cooled in AX, the refrigerant vapor from GX is absorbed. A low temperature heat exchanger XL is provided for heat exchange between the concentrated solution supplied from GX to A, and the diluted solution sent from AX to G, and a high temperature heat exchanger XH is provided for heating the diluted solution leaving from XL and sent to G with the concentrated solution supplied from G to GX.

TECHNICAL FIELD

The present invention relates to an absorption refrigerating machine andmore particularly to an absorption refrigerating machine for utilizingas a heat source, hot water at relatively low temperatures for example60 to 70 degrees Celsius such as from engine cooling exhaust heat (hotwater in engine jackets), cooling exhaust heat from industrialprocesses, or recovered hot water heat from boiler exhaust gases.

BACKGROUND ART

Exhaust heat at relatively low temperatures of 60 to 70 degrees Celsiussuch as from engine cooling exhaust heat (hot water in engine jackets)or cooling exhaust heat from industrial processes is present in largequantities throughout the world. However, there are few uses for thistype of exhaust heat since the temperature is low, so that this exhaustheat is directly discarded or indirectly discarded via a cooling tower.

An absorption refrigerating machine for producing cold water usingexhaust heat water as a heat source is known in the related art. Anexample for producing cold water at approximately 7 degrees Celsius forair conditioning from cooling water at 30 to 31 degrees Celsius as acooling source by using a cooling tower is shown by the single effectabsorption cycle plotted on the Dühring diagram in FIG. 14.

Refrigerant is evaporated in the evaporator E. The refrigerant shiftsalong the dashed line between E and A in the figure and is absorbed inthe absorber A. The diluted solution whose concentration has dropped isheated in the regenerator G with an external heat source. Refrigerantvapor is discharged in a quantity equal to that of the refrigerantevaporated in the evaporator E, and the diluted solution is concentratedand returned to the absorber A. A heat exchanger X is utilized (for heatexchange between the concentrated solution side X2 and the dilutedsolution side X1) at this time to recover the heat. The refrigerantvapor generated in the regenerator G shifts along the dashed linebetween G and C in the figure, is condensed in the condenser C andbecomes refrigerant liquid. This refrigerant liquid returns from thecondenser C to the evaporator E.

When the evaporation temperature is 5 degrees Celsius, the absorberoutlet temperature is 35 degrees Celsius, and the condensationtemperature is 35 degrees Celsius, the solution temperature of theregenerator reaches 69 to 74 degrees Celsius. The temperature of the hotwater inlet serving as the heat source needs about 75 degrees Celsius.

In other words, in the single effect absorption refrigerating machine,hot water at the temperature of the 65 to 70 degrees Celsius serving asthe heat source is too low in the temperature to produce the cold waterat approximately 7 degrees Celsius.

There is also a commercial double-concentrating type absorptionrefrigerating machine capable of producing cold water of less than 10degrees Celsius for air conditioning applications, using exhaust heatwater of around 60 to 65 degrees Celsius as the heat source, and coolingwater from a cooling tower of about 30 to 31 degrees Celsius as thecooling source.

In the example shown in FIG. 15, both the regenerators GL, GH haveapproximately the same heat transfer area, and both the absorbers AL, AHhave approximately the same heat transfer area in thedouble-concentrating absorption cycle plotted on the Dühring diagram.This figure shows an example cycle of this general heat transfer arearelationship.

The refrigerant evaporates in the evaporator E, shifts along the dashedline between E and AL in the figure, and is absorbed in the absorber AL.

The diluted solution whose concentration has dropped is heated with anexternal heat source in the low-pressure regenerator GL. Refrigerantvapor is discharged in a quantity equal to that of the refrigerantevaporated in the evaporator, the diluted solution is concentrated andreturned to the absorber AL. At this time, a low-temperature heatexchanger XL (for heat exchange between the concentrated solution sideXL2 and the diluted solution side XL1) is utilized for recovering theheat.

The refrigerant vapor generated in the low-pressure regenerator GLshifts along the dashed line between GL-AH in the figure, and isabsorbed in the high-pressure absorber AH. The diluted solution whoseconcentration has dropped in the high-pressure absorber AH is heatedwith an external heat source in the high-pressure regenerator GH.Refrigerant vapor is discharged in a quantity equal to that of therefrigerant generated in the low-pressure regenerator GL, or in otherwords the same quantity as that of the refrigerant evaporated by theevaporator E. The diluted solution is then concentrated and returned tothe high-pressure absorber AH. A high-temperature heat exchanger XH (forheat exchange between the concentrated solution side XH2 and the dilutedsolution side XH1) is utilized for recovering the heat from thesolution.

The refrigerant vapor generated in the high-pressure regenerator GHshifts along the dashed line between GH and C in the figure, iscondensed in the condenser C, and becomes refrigerant liquid. Thisrefrigerant liquid returns from the condenser C to the evaporator E.

The double-concentrating type absorption refrigerating machine thereforecontains many internal devices and is large in size. Moreover, thehigh-pressure regenerators GH and the low-pressure regenerator GL needto generate refrigerant vapor equal in quantity to that of therefrigerant vapor generated by the evaporator E two times. Theefficiency is therefore less than half of that of the single effectabsorption refrigerating machine. Therefore the double-concentratingtype absorption refrigerating machine has been seldom used.

There is also an absorption refrigerating machine capable of operatingwith exhaust heat water of approximately 65 degrees Celsius as a heatsource. However, this refrigerating machine is even larger than thedouble-concentrating type absorption refrigerating machine, and isexpensive, and has low heat efficiency, and therefore is seldomutilized.

There is also an absorption refrigerating machine having a high-pressureand low-pressure absorbers and regenerators (FIG. 16), as is anabsorption refrigerating machine intermediate between the single effectand the double-concentrating type absorption refrigerating machines.This type of absorption refrigerating machine is somewhat smaller insize than the double-concentrating type absorption refrigerating machineand has better heat efficiency. Yet an absorption refrigerating machinewith better heat efficiency has been demanded.

In FIG. 16, the refrigerant evaporates in the evaporator E, shifts alongthe dashed line between E and A in the figure, and is absorbed in theabsorber A. The diluted solution of the absorber outlet port whoseconcentration is reduced, is sent to the auxiliary absorber AX, andwhile being cooled in the auxiliary absorber AX, absorbs the refrigerantvapor (shifting along the dashed line between GX and AX in the figure)from the auxiliary regenerator GX.

The diluted solution, from the auxiliary absorber AX whose concentrationis reduced, is sent to the regenerator G, and is heated and concentratedwith the external heat source in the regenerator. The refrigerant vaporthat was generated, shifts along the dashed line between G and C in thefigure, is condensed in the condenser C and becomes refrigerant liquid.This refrigerant liquid returns from the condenser C to the evaporatorE. The solution concentrated in regenerator G on the other hand, isfurther heated and concentrated with the external heat source in theauxiliary regenerator GX, and returns to the absorber A. The refrigerantvapor that was generated, shifts along the dashed line between GX and AXin the figure and is absorbed in the auxiliary absorber AX.

In the solution circulating system in this cycle, a solution pump isrequired in order to feed the solution from the absorber A to theauxiliary absorber AX having a higher pressure than the absorber. Asolution pump is also required for feeding solution from the auxiliaryabsorber AX to the regenerator G. Balance control of solution flow rateis also required for feeding the total flow rate from the auxiliaryabsorber AX to the regenerator C, and therefore, the system iscomplicated.

In other words, when the quantity fed from the auxiliary absorber to theregenerator is too small, solution collects in the auxiliary absorber,and the solution quantity in the regenerator to auxiliary regenerator toabsorber system becomes small, and ultimately cavitation occurs due toinsufficient quantity of the solution in the solution pump for sendingthe solution from the absorber to the auxiliary absorber, so thatoperation is disabled. On the other hand, if the quantity fed from theauxiliary absorber to the regenerator is too large, then the solutionquantity of auxiliary absorber is insufficient so that cavitation occursin the solution pump for sending the solution from the auxiliaryabsorber to the regenerator and operation is disabled. Therefore,control or the like is required to balance the solution flow rates intoand out of the auxiliary absorber.

In view of the above problems with the conventional art, presentinvention has the object to provide a compact absorption refrigeratingmachine with improved heat exchanger disposing positioning, betterefficiency, and capable of using hot water at 60 to 70 degrees Celsiusas a heat source.

DISCLOSURE OF THE INVENTION

As shown for example in FIG. 1, to attain the aforementioned object, theabsorption refrigerating machine of the present invention is providedwith a regenerator G for generating refrigerant vapor and concentratinga solution; a condenser C for condensing the generated refrigerantvapor; an evaporator E for evaporating the condensed refrigerant; anabsorber A for absorbing the evaporated refrigerant vapor into thesolution; an auxiliary regenerator GX for heating the concentratedsolution from the regenerator G, generating the refrigerant vapor andfurther concentrating the solution; an auxiliary absorber AX forabsorbing the refrigerant vapor generated in the auxiliary regeneratorwhile cooling a diluted solution from the absorber A; a low-temperatureheat exchanger XL for performing heat exchange between the concentratedsolution sent from the auxiliary regenerator GX to the absorber A andthe diluted solution sent from the auxiliary absorber AX to theregenerator G; a high-temperature heat exchanger XH for heating thediluted solution leaving the low-temperature heat exchanger XL and sentto the regenerator G with the concentrated solution sent from theregenerator G to the auxiliary regenerator GX.

The absorption refrigerating machine of the present invention may alsobe provided with a regenerator G for generating refrigerant vapor andconcentrating a solution; a condenser C for condensing the generatedrefrigerant vapor; an evaporator E for evaporating the condensedrefrigerant; an absorber A for absorbing the evaporated refrigerantvapor into the solution and; an auxiliary regenerator GX for heating theconcentrated solution from the regenerator G, generating the refrigerantvapor and further concentrating the solution; an auxiliary absorber AXfor absorbing the refrigerant vapor generated in the auxiliaryregenerator GX while cooling a diluted solution from the absorber A,wherein a heat transfer area of the auxiliary regenerator GX is equal toor smaller than one-third of a heat transfer area of the regenerator G,and a heat transfer area of the auxiliary absorber AX is equal to orsmaller than two-thirds of a heat transfer area of the absorber A.

As shown for example in FIG. 7, the absorption refrigerating machine ofthe present invention may be provided with a regenerator G forgenerating refrigerant vapor and concentrating a solution; a condenser Cfor condensing the generated refrigerant vapor; an evaporator E forevaporating the condensed refrigerant; an absorber A for absorbing theevaporated refrigerant vapor into the solution; an auxiliary regeneratorGX for heating the concentrated solution from the regenerator G,generating the refrigerant vapor and further concentrating the solution;an auxiliary absorber AX for absorbing the refrigerant vapor generatedin the auxiliary regenerator GX while cooling a diluted solution fromthe absorber A; a circulating path 1, 2, 3, 4 for allowing the solutionto reach the absorber A in sequence from the absorber A, the auxiliaryabsorber AX, the regenerator G, and the auxiliary regenerator GX; and atleast one of means VGH, VGS for controlling heat transfer performance ofthe auxiliary regenerator GX and means VAW, VAS for controlling heattransfer performance of the auxiliary absorber AX.

As shown for example in FIG. 9, the absorption refrigerating machine ofthe present invention may be provided with a regenerator G forgenerating refrigerant vapor and concentrating a solution; a condenser Cfor condensing the generated refrigerant vapor; an evaporator E forevaporating the condensed refrigerant; an absorber A for absorbing theevaporated refrigerant vapor into the solution; an auxiliary regeneratorGX for heating the concentrated solution from the regenerator,generating the refrigerant vapor and further concentrating the solution;and an auxiliary absorber AX for absorbing the refrigerant vaporgenerated in the auxiliary regenerator GX while cooling the dilutedsolution, the auxiliary absorber AX being constructed to utilize as thediluted solution a portion of diluted solution mixture made up of thediluted solution of the absorber A outlet and the diluted solution ofthe auxiliary absorber AX outlet; a path 2 for sending the remainder ofthe diluted solution mixture to the regenerator G; a low-temperatureheat exchanger XL for heating the diluted solution mixture sequentiallyon the path 2 with the concentrated solution supplied from the auxiliaryregenerator GX to the absorber A; and a high-temperature heat exchangerXH for heating the diluted solution mixture leaving from thelow-temperature heat exchanger XL and sent to the regenerator G with theconcentrated solution supplied from the regenerator G to the auxiliaryregenerator GX.

Also, the absorption refrigerating machine of the present invention maybe provided, wherein, as shown for example in FIG. 5 and FIG. 12, theabsorber A is subdivided into a low-pressure absorber AL and ahigh-pressure absorber AH, the evaporator E is subdivided into alow-pressure evaporator EL and a high-pressure evaporator EH, the coldwater 10 is first of all supplied to the high-pressure evaporator EH,the cooled cold water 10 is next supplied to the low-pressure evaporatorEL, as shown for example in FIG. 5, the concentrated solution from theauxiliary regenerator GX is first of all supplied to the low-pressureabsorber AL, the refrigerant vapor from the low-pressure evaporator ELis absorbed, the solution absorbing the refrigerant vapor in thelow-pressure absorber AL is supplied to the high-pressure absorber AH,the refrigerant vapor from the high-pressure evaporator EH is absorbed,and the diluted solution absorbing the refrigerant vapor is supplied tothe auxiliary absorber AX. Also, as shown for example in FIG. 12, theabsorption refrigerating machine of the present invention may be soconstituted that the concentrated solution from the regenerator G isfirst of all supplied to the low-pressure absorber AL, the refrigerantvapor from the low-pressure evaporator EL is absorbed, the solutionabsorbing the refrigerant vapor in the low-pressure absorber AL issupplied to the high-pressure absorber AH, and the refrigerant vaporfrom the high-pressure evaporator EH is absorbed, a portion of thediluted solution mixture of the diluted solution of the high-pressureabsorber AH outlet absorbing the refrigerant vapor and the dilutedsolution of the auxiliary absorber AX outlet is supplied to theauxiliary absorber AX, and the remainder is sent to the regenerator G.

The present application is based on the Japanese Patent Application No.2002-280111 filed on Sep. 26, 2002 in Japan, the Japanese PatentApplication No. 2002-280112 filed on Sep. 26, 2002, and the JapanesePatent Application No. 2003-166181 filed on Jun. 11, 2003. TheseJapanese Patent Applications are hereby incorporated in its entirety byreference into the present application.

The present application will become more fully understood from thedetailed description given hereinbelow. However, the detaileddescription and the specific embodiment are illustrated of desiredembodiments of the present invention and are described only for thepurpose of explanation. Various changes and modifications will beapparent to those ordinary skilled in the art of the basic of thedetailed description.

The applicant has no intention to give to public any disclosedembodiment. Among the disclosed changes and modifications, those whichmay not literally fall within the scope of the patent claims constitute,therefore, a part of the present invention in the sense of doctrine ofequivalents.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural flow diagram showing the absorption refrigeratingmachine of the first embodiment of this invention;

FIG. 2 is a Dühring diagram of the solution cycle of FIG. 1;

FIG. 3 is a graph showing the interrelation of the refrigerant vaporshift rate between GX-AX in FIG. 1 with the required hot water inlettemperature, and with the COP;

FIG. 4 is a graph showing the interrelation of the refrigerant vaporshift rate between GX-AX in FIG. 1 with the hot water inlet temperatureat certain the cooling water inlet temperatures;

FIG. 5 is a structural flow diagram showing the absorption refrigeratingmachine of the second embodiment of this invention;

FIG. 6 is a Dühring diagram of the solution cycle of FIG. 5;

FIG. 7 is a structural flow diagram showing the absorption refrigeratingmachine of the third embodiment of this invention;

FIGS. 8( a) and 8(b) are a Dühring diagrams of the solution cycle ofFIG. 7 partially modified;

FIG. 9 is a schematic structural diagram showing the absorptionrefrigerating machine of the fourth embodiment of this invention;

FIG. 10 is a schematic structural diagram showing the absorptionrefrigerating machine of the fifth embodiment of this invention;

FIG. 11 is a Dühring diagram of the solution cycle with respect to FIG.9;

FIG. 12 is a schematic structural diagram showing the absorptionrefrigerating machine of the sixth embodiment of this invention;

FIG. 13 is a Dühring diagram of the solution cycle with respect to FIG.12;

FIG. 14 is a Dühring diagram of the single effect absorption cycle;

FIG. 15 is a Dühring diagram of the double-concentrating type absorptioncycle;

FIG. 16 is a Dühring diagram of the cycle combining two separate systemsfor the double-concentrating type absorption cycle of the known art.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be herein after described in detail withreference to the drawings. The embodiments of the present invention aredescribed next, however, the scope of the present invention is notlimited by these embodiments.

FIG. 1 is a structural flow diagram showing the absorption refrigeratingmachine of the first embodiment of this invention.

In FIG. 1, a reference symbol E is an evaporator, A is an absorber, G isa regenerator, C is a condenser, AX is an auxiliary absorber, GX is anauxiliary regenerator, XL is a low-temperature heat exchanger, XH is ahigh-temperature heat exchanger, SP is a solution pump, RP is arefrigerant pump, V1 is a three-way valve, the reference numerals 1through 4 are solution flow paths, 5 is a refrigerant vapor flow path,the numerals 6, 7 are refrigerant flow paths, 8 is hot water, 9 iscooling water, and 10 is cold water.

In this embodiment, the evaporator E and the absorber A are formed inone space with an eliminator between the evaporator E and the absorberA. The regenerator G and the condenser C are formed in another separatespace with another eliminator between the regenerator G and thecondenser C. The auxiliary absorber AX, the auxiliary regenerator GX,the low-temperature heat exchanger XL, and the high-temperature heatexchanger XH are each formed in the separate shells.

A refrigerant pump RP is installed on the refrigerant flow path 7 forcirculating the refrigerant in order to disperse the refrigerant to atube for flow of the cold water 10 in the evaporator E.

The auxiliary absorber AX and the regenerator G are connected by thesolution flow path 2 for sending the diluted solution from the auxiliaryabsorber AX to the regenerator G. A low-temperature heat exchanger XLand a high-temperature heat exchanger XH are placed in that order alongthe solution flow path 2. A solution pump SP is installed between theauxiliary absorber AX and the low-temperature heat exchanger XL.

The absorber A and the auxiliary absorber AX are connected by thesolution flow path 1 for sending the diluted solution from the absorberA to the auxiliary absorber AX.

The regenerator G and the auxiliary regenerator GX are connected by thesolution flow path 3 for sending the concentrated solution from theregenerator G to the auxiliary regenerator GX. The high-temperature heatexchanger XH is installed on the solution flow path 3.

The auxiliary regenerator GX and the absorber A are connected by thesolution vapor flow path 4 for sending the solution from the auxiliaryregenerator GX to the absorber A. The low-temperature heat exchanger XLis installed on the solution flow path 4.

The auxiliary regenerator GX and the auxiliary absorber AX are connectedby the solution flow path 5 for sending the refrigerant vapor from theauxiliary regenerator GX to the auxiliary absorber AX.

Between the condenser C and the evaporator E, the refrigerant flow path6 is disposed for sending the refrigerant liquid from the condenser C tothe evaporator E.

A hot water pipe 81 for allowing the flow of hot water 8 as the heatsource fluid for heating the solution is laid extending from theregenerator G to the auxiliary regenerator GX. The hot water 8 first ofall flows via the hot water pipe 81 into the regenerator G, and alsoflows via the hot water pipe 81 into the auxiliary regenerator GX.

A three-way valve V1 for controlling the flow rate of hot water passingthrough the auxiliary regenerator GX is disposed on the outlet side ofthe auxiliary regenerator GX in the hot water pipe 81. This three-wayvalve V1 may be disposed on the inlet side of the auxiliary regeneratorGX in the hot water pipe 81.

A cooling water pipe 91 for the flow of the cooling water 9 as therefrigerant substance for cooling the solution is laid from the absorberA to the condenser C, and to the auxiliary absorber AX. This coolingwater 9 first of all flows via the cooling water pipe 91 into theabsorber A, and also flows via the cooling water pipe 91 to thecondenser C, and then flows to the auxiliary absorber AX.

In the absorption refrigerating machine of FIG. 1, the concentratedsolution supplied to the absorber A, absorbs the refrigerant vapor fromthe evaporator E while being cooled by the cooling water 9, and becomesa diluted solution. The diluted solution from the absorber A is suppliedfrom the flow path 1 to the auxiliary absorber AX, and absorbs therefrigerant vapor from the flow path 5 generated in the auxiliaryregenerator GX while being cooled by the cooling water, and also becomesa low-concentration diluted solution.

The pressure of the diluted solution leaving the auxiliary absorber AXthrough the flow path 2 is raised by the solution pump SP and enters thelow-temperature heat exchanger XL, subjected to heat exchange in thelow-temperature heat exchanger XL with the concentrated solution flowingfrom the auxiliary regenerator GX via the flow path 4 towards theabsorber A. With this heat exchange the temperature of the dilutedsolution rises while the temperature of the concentrated solutionlowers. The high-temperature heat exchanger XH next performs heatexchange of the diluted solution with the concentrated solution flowingfrom the regenerator G to the auxiliary regenerator GX, and thetemperature of the diluted solution rises even further, while thetemperature of the concentrated solution drops.

The solution in the regenerator G is heated by the hot water 8functioning as the heat source, generates refrigerant vapor and thesolution is concentrated. The concentrated solution which is thusconcentrated enters the auxiliary regenerator GX via the heating side ofthe high-temperature heat exchanger XH from the flow path 3, is heatedby the hot water 8 functioning as the heat source to generaterefrigerant vapor, and further concentrated, and supplied from the flowpath 4 to the absorber A via the heating side of the low-temperatureheat exchanger XL, to complete one solution cycle.

In the evaporator E, the refrigerant liquid cools the cold water 10 withthe latent heat of vaporization, forms refrigerant vapor, and isabsorbed into the solution in the absorber A. The refrigerant vaporgenerated in the regenerator G, is cooled by the cooling water 9 in thecondenser C, becomes refrigerant liquid, and is supplied from the flowpath 6 to the evaporator E.

In contrast to the solution cycle for the double-concentrating cycle ofthe conventional art separated into two systems (FIG. 15), this solutioncycle is a single-system circulating cycle. Moreover, the heat energy inthe concentrated solution heated in the auxiliary regenerator GX isrecovered in the diluted solution flowing from the auxiliary absorber AXtowards the regenerator G. Likewise, the heat energy in the concentratedsolution heated in the generator G is further recovered in the abovementioned diluted solution.

Next, the cycle in the Dühring diagram of FIG. 2 is described.

The solution cycle of FIG. 1 is shown in the Dühring diagram in FIG. 2.

In order to lower to the required hot water temperature in the presentembodiment, the cycle concentration is changed using the auxiliaryregenerator GX and the auxiliary absorber AX. The heat transfer area ofthe auxiliary regenerator GX and the auxiliary absorber AX may be setaccording to the corresponding hot water temperature. The figure showsan example when the heat transfer area of the auxiliary regenerator GXis set to approximately 5% of that of the regenerator G, and the heattransfer area of the auxiliary absorber AX is set to approximately 20%of that of the absorber A.

In the auxiliary regenerator GX, there is a large differential betweenthe heat source temperature and the solution temperature so that theheat transfer area of the auxiliary regenerator GX is small. Due to thistemperature relation, preferably, the inlet of the regenerator G is setto be the high-temperature side of the hot water forming the heatsource, and the outlet of the regenerator G is set to be thelow-temperature side of the hot water, and thus the hot water is firstsupplied to the regenerator G and is next supplied to the auxiliaryregenerator GX.

The refrigerant vaporizes in the evaporator E, shifts between E and A onthe dashed line in FIG. 2, and is absorbed in the absorber A.

The solution leaving the absorber A enters the auxiliary absorber AXwith the same temperature and same concentration, absorbs therefrigerant vapor that is generated in the auxiliary regenerator GX andshifts from GX to AX in FIG. 2, and forms the diluted solution with aneven lower concentration. This diluted solution passes along the heatedside XL1 of the low-temperature heat exchanger XL, and is heated by theconcentrated solution supplied from the auxiliary regenerator GX to theabsorber A via the heating side XL2 of the low-temperature heatexchanger XL in the low-temperature heat exchanger XL. This dilutedsolution further passes along the heated side XH1 of thehigh-temperature heat exchanger XH, is heated by the concentratedsolution supplied from the regenerator G to the auxiliary regenerator GXvia the heating side XH2 of the high-temperature heat exchanger, andenters the regenerator G. The regenerator G discharges the quantity ofthe refrigerant vapor that is absorbed in the absorber A, forming aconcentrated solution. This concentrated solution enters the auxiliaryregenerator GX via the heating side XH2 of the high-temperature heatexchanger XH, is heated by the external heat source, discharges thequantity equal to the quantity of refrigerant absorbed in the auxiliaryabsorber AX, is further concentrated, and enters the absorber A via theheating side XL2 of the low-temperature heat exchanger XL.

In the present embodiment, the heat retained in the concentratedsolution from the auxiliary regenerator GX towards the absorber A, is inthis way recovered in the diluted solution flowing from the auxiliaryabsorber AX towards the regenerator G, rather than the diluted solutionshifting from the absorber A towards the auxiliary absorber AX, and theheat retained in the concentrated solution flowing from the regeneratorG towards the auxiliary regenerator GX is recovered. The temperature ofthe solution entering the absorber G can rise due to this heat recoveryand the amount of heat required in the regenerator G for heating thesolution can be reduced. Moreover, the temperature of the solutionentering the auxiliary regenerator GX via the heating side XH2 of thehigh-temperature heat exchanger can be raised higher than the case wherethe diluted solution from the auxiliary absorber AX towards theregenerator G is not heated on the heated side XL2 of thelow-temperature heat exchanger, and the amount of heat required forheating the solution in the auxiliary regenerator GX can be reduced.

FIG. 3 and FIG. 4 are graphs showing the interrelation of therefrigerant vapor shift rate and the hot water inlet temperature betweenthe auxiliary regenerator GX and the auxiliary absorber AX.

The flow rate of the refrigerant vapor generated in the auxiliaryregenerator GX and absorbed in the auxiliary absorber AX corresponds tothe flow rate which causes lower efficiency compared with the singleeffect absorption refrigerating machine. If this vapor flow rate isreduced to zero, then the efficiency is equivalent to that of the singleeffect absorption refrigerating machine, and if this vapor flow rate ismade to be equal to evaporation rate of the evaporator E, then theefficiency is equivalent to that of the double-concentrating type. Thecycle concentration changes due to the flow rate of refrigerant vaporgenerated in the auxiliary regenerator GX and absorbed in the auxiliaryabsorber AX so that the required heat source temperature changes. FIG. 3shows this relation. In this figure, the heat transfer area of theauxiliary regenerator GX is approximately 15% of that of heat transferarea of the regenerator G, moreover the heat transfer area of theauxiliary absorber AX is approximately 50% of that of the absorber A, solimits are applied to the heat transfer capability of the regenerator Gto change the flow rate of refrigerant vapor.

If the heat source temperature for example is about 65 to 70 degreesCelsius, then the flow rate of refrigerant vapor shifted between theauxiliary regenerator GX and auxiliary absorber AX may be half the flowrate vaporized in the evaporator E. Therefore, when an absorptionrefrigerating machine is designed under these conditions, the auxiliaryregenerator GX and auxiliary absorber AX may both be respectively lessthan, or equal to half the size of the regenerator G and absorber A, sothat a more compact body can be employed than when using thedouble-concentrating type absorption refrigerating machine. Furthermore,the efficiency can be improved.

Up until the heat transfer area of the auxiliary regenerator GX reachesone-third of that of the generator G or in particular approximately 20%,and the heat transfer area of the auxiliary absorber AX reachestwo-thirds of that of the absorber A or in particular approximately 60%,the concentration at the absorber outlet is lower than the concentrationat the regenerator outlet, and in most cases, the efficiency is betterthan that of the full double-concentrating type absorption refrigeratingmachine whose cycles are separate.

When the temperature of the cooling water drops, the solutionconcentration required for obtaining the same cold water temperaturedrops, and the heat source temperature required for the solutionconcentration drops. FIG. 4 shows the hot water temperature required forthe case in which the cooling water temperature changes. Therefore, evenif the heat source temperature that can be supplied is the same, whenthe cooling water temperature has dropped, the flow rate of refrigerantvapor generated in the auxiliary regenerator GX and absorbed in theauxiliary absorber AX can be reduced, and the efficiency can beimproved.

The flow rate of refrigerant vapor generated in the auxiliaryregenerator GX and absorbed in the auxiliary absorber AX can be adjustedif for example a three-way valve V1 as shown in FIG. 1, is disposed forcontrolling the flow rate of hot water supplied to the auxiliaryregenerator GX. Also, a portion or all of the solution flow rate to theauxiliary regenerator GX can be bypassed to change the flow rate ofgenerated vapor, or a portion or all of the solution flow rate to theauxiliary absorber AX can be bypassed to permit changing the flow rateof absorbed vapor. The flow rate of cooling water to the auxiliaryabsorber AX may also be changed.

In the present embodiment, the efficiency can be continuously changed,from that of the double-concentrating cycle to that of the single effectabsorption cycle by controlling the flow rate of refrigerant vaporgenerated in the auxiliary regenerator GX and absorbed in the auxiliaryabsorber AX. This can be effectively done to increase the efficiencywhen the hot water temperature has risen or the cooling watertemperature has dropped.

FIG. 5 is a structural flow diagram showing the absorption refrigeratingmachine of the second embodiment of this invention.

In FIG. 5, reference numerals identical to those in FIG. 1 have the samemeaning. In FIG. 5, in order to utilize the difference in the cold waterinlet/outlet temperatures to further improve efficiency, the absorber Aof the above absorption refrigerating machine is subdivided into alow-pressure absorber AL and a high-pressure absorber AH, and theevaporator E is subdivided into a low-pressure evaporator EL and ahigh-pressure evaporator EH. The low-pressure absorber AL and thelow-pressure evaporator EL are formed in one space with an eliminatorbetween the low-pressure absorber AL and the low-pressure evaporator EL.The high-pressure absorber AH and the high-pressure evaporator EH areformed in another separate space with an eliminator between thehigh-pressure absorber AH and the high-pressure evaporator EH.

The cooling water pipe 91 is laid to allow parallel flow into thelow-pressure absorber AL and the high pressure absorber AH. The coldwater pipe 10 a is laid to allow flow in series from the high-pressureevaporator EH to the low-pressure evaporator EL in this order.

The solution flow path 4 is laid connecting to the low-pressure absorberAL, from the auxiliary regenerator GX via the low-temperature heatexchanger XL. The solution flow path 4 is laid so as to supply thesolution from the low-pressure absorber AL to the high-pressure absorberAH.

In the present embodiment, the cold water 10 is first of all supplied tothe high-pressure evaporator EH, and the cooled cold water 10 is nextsupplied to the low-pressure evaporator EL, and the concentratedsolution from the auxiliary regenerator GX is first of all supplied tothe low-pressure absorber AL, and absorbs the refrigerant vapor from thelow-pressure evaporator EL, and the solution absorbing the refrigerantvapor in the low-pressure absorber AL is supplied to the high-pressureabsorber AH, and absorbs the refrigerant vapor from the high-pressureevaporator EH.

The solution absorbing the refrigerant vapor in the high-pressureabsorber AH, passes from the flow path 1 through the auxiliary absorberAX, and is fed from the flow path 2 to the regenerator G via thelow-temperature heat exchanger XL and the high-temperature heatexchanger XH and the solution concentrated in the regenerator G is fedfrom the flow path 3 via the high-temperature heat exchanger XH to theauxiliary regenerator GX, and further from the flow path 4 via thelow-temperature heat exchanger XL to the low-pressure absorber AL.

FIG. 6 is a Dühring diagram showing the solution cycle in regard to FIG.5. The saturation temperature of the high-pressure evaporator EH isincreased, and the concentration of the diluted solution leaving thehigh-pressure absorber AH is decreased.

In this way, the flow rate of refrigerant required for furtherdecreasing the concentration in the auxiliary absorber AX can bereduced, and the efficiency can be increased compared to the case ofFIG. 1.

FIG. 7 is a structural flow diagram showing the absorption refrigeratingmachine of the third embodiment of this invention.

In FIG. 7, the point differing from the first embodiment described inFIG. 1 is that the embodiment contains the flow rate control valves VGH,VGS, VAW, VAS. In the present embodiment, these are three-way valves.

The flow rate control valve VGH is placed on the hot water pipe 81 inthe same manner as the three-way valve V1 described in the firstembodiment.

The flow rate control valve VGS is placed on the solution flow path 3connecting the high-temperature heat exchanger XH and the auxiliaryregenerator GX. One port of the three-way valve VGS connects to thesolution flow path 4 that connects the auxiliary regenerator GX and thelow-temperature heat exchanger XL.

The flow rate control valve VAW is disposed on the outlet side of theauxiliary absorber AX in the cooling water pipe 91. The three-way valveVAW may be disposed on the inlet side of the auxiliary absorber AX inthe cooling water pipe 91.

The flow rate control valve VAS is placed on the solution flow path 1connecting the absorber A and the auxiliary absorber AX. One port of thethree-way valve VAS connects, between the solution pump SP and theauxiliary absorber AX, to the solution flow path 2 for connecting theauxiliary absorber AX and the low-temperature heat exchanger XL.

The Dühring cycle of the present embodiment is identical with thatdescribed in FIG. 1.

FIG. 8 shows the Dühring cycle for the modified example of the thirdembodiment. As shown in FIG. 8( a), although there is some amount ofsacrifice in efficiency, the low-temperature heat exchanger XL isomitted and a compact design can be attained. Also, as shown in FIG. 8(b), the heated side XL1 of the low-temperature heat exchanger XL canmake diluted solution from the absorber towards the auxiliary absorber.

The interrelation of the refrigerant vapor shift rate and the hot waterinlet temperature and between the auxiliary regenerator GX auxiliaryabsorber AX is the same as described in the first embodiment.

The flow rate of refrigerant vapor generated in the auxiliaryregenerator GX and absorbed in the auxiliary absorber AX can be adjustedthe same as in the first embodiment if, for example as shown in FIG. 7,a three-way valve VGH is provided to adjust the flow rate of hot watersupplied to the auxiliary regenerator GX. Also, the solution valve VGSshown in FIG. 7, can limit the flow rate of generated vapor by bypassinga portion or all of the solution flow rate to the auxiliary regeneratorGX as shown by the dashed line, and the flow rate of refrigerant vaporshifting between GX and AX can be varied. Also, in FIG. 7, by using thecooling water valve VAW, the flow rate of cooling water to the auxiliaryabsorber AX can be changed, or by using the solution valve VAS in FIG.7, a portion or all of the solution flow rate to the auxiliary absorberAX can be bypassed to change it, and therefore, the flow rate ofabsorbed vapor can be limited, to allow changing the flow rate ofrefrigerant vapor shifting between GX and AX.

In the present embodiment, the flow rate of refrigerant vapor generatedin the auxiliary regenerator GX and absorbed in the auxiliary absorberAX can be adjusted so that the efficiency can be continuously changedfrom that of the double-concentrating cycle absorption to that of thesingle effect absorption cycle. This can be effectively done to increasethe efficiency when the hot water temperature rises or the cooling watertemperature drops.

FIG. 9 is a schematic structural diagram showing the absorptionrefrigerating machine of the fourth embodiment of this invention.

As shown in FIG. 9, the refrigerating machine of the present embodimentis constituted, including an evaporator E, an absorber A, a regeneratorG, a condenser C, an auxiliary absorber AX, an auxiliary regenerator GX,a low-temperature heat exchanger XL, and a high-temperature heatexchanger XH.

The point where the present embodiment differs from the first embodimentis that the solution flow path 1 a from the absorber A, merges with thesolution flow path 2 a from the auxiliary absorber AX to flow into thesolution pump SP, and that the solution flow path 1 b to the auxiliaryabsorber AX branches from the solution flow path 2 from the outlet ofthe solution pump SP.

In this type of structure, the concentrated solution supplied to theabsorber A absorbs refrigerant vapor from the evaporator E while beingcooled by the cooling water 9 and becomes diluted solution. The dilutedsolution from the absorber A, along with the diluted solution from theauxiliary absorber AX are pressurized with the solution pump SP andforms the solution mixture. A portion of the mixed diluted solution issupplied to the auxiliary absorber AX, and absorbs the refrigerant vaporgenerated in the auxiliary regenerator GX while being cooled by thecooling water 9, and becomes a further diluted solution with a lowerconcentration.

The remainder of the diluted solution mixture whose pressure was raisedin the solution pump SP enters the low-temperature heat exchanger XL,and heat exchange with the concentrated solution from the auxiliaryregenerator GX towards the absorber A is performed by thelow-temperature heat exchanger XL, the temperature of the dilutedsolution mixture rises while the temperature of the concentratedsolution drops. The diluted solution mixture then enters thehigh-temperature heat exchanger XH, heat exchange with the concentratedsolution from the regenerator G to the auxiliary regenerator GX isperformed by the high-temperature heat exchanger XH, and the temperatureof the diluted solution mixture rises even further while the temperatureof the concentrated solution drops. The solution in the regenerator G isheated by the hot water functioning as the heat source, generatesrefrigerant vapor and is concentrated. The concentrated solution whichis thus concentrated enters the auxiliary regenerator GX via the heatingside of the high-temperature heat exchanger XH, and is heated by the hotwater of the heat source and generates refrigerant vapor, is furtherconcentrated, and supplied into the absorber A via the heating side ofthe low-temperature heat exchanger XL, to complete one solution cycle.In the evaporator E, the refrigerant liquid cools the cold water withthe latent heat of vaporization, changes it to refrigerant vapor, andthe refrigerant vapor is absorbed into the solution of the absorber A.The refrigerant vapor generated in the regenerator G is cooled in thecondenser C with the cooling water 9, and becomes refrigerant liquid andis supplied to the evaporator E.

In contrast to the solution cycle for the double-concentrating cycle ofthe conventional art that is separated into two systems (FIG. 15), thissolution cycle is a single-system circulating cycle. Moreover, in thisstructure, the heat energy in the concentrated solution heated in theauxiliary regenerator GX is recovered in the diluted solution from theauxiliary absorber AX towards the regenerator G. This structure is alsocharacterized in that the heat energy in the concentrated solutionheated in the regenerator G is further recovered in the above mentioneddiluted solution.

In this cycle between the conventional single effect and thedouble-concentrating types, the solution circulating system requires asolution pump for the absorber outlet and a solution pump for theauxiliary absorber outlet. A control to balance the flow rates of thesolution entering and leaving the auxiliary absorber is also required.

In the cycle of the present embodiment, the solution from the auxiliaryabsorber AX is not sent to the regenerator G, rather the solution issent from the auxiliary absorber AX to the outlet side of the absorber Awhich is at a lower pressure so that no solution pump is required at theoutlet of the auxiliary absorber AX.

The outlet of the auxiliary absorber AX may be used simply for theoutflow of solution so that no special flow rate balance control isneeded and a compact design can be attained.

FIG. 11 is a cycle on a Dühring diagram and shows the solution cycle ofFIG. 9 on the Dühring diagram.

In the refrigerant vapor shifting rate between the auxiliary regeneratorGX and auxiliary absorber AX, the refrigerant vapor flow rate generatedin the auxiliary regenerator GX and absorbed in the auxiliary absorberAX corresponds to an efficiency drop from the efficiency of the singleeffect absorption refrigerating machine. If this vapor flow rate isreduced to zero, then the efficiency is equivalent to that of asingle-effect type, and if this vapor flow rate is made to be equal tothat evaporated in the evaporator E, then the efficiency is equivalentto that of a double-concentrating type.

In other words, when the flow rate of refrigerant vapor generated in theauxiliary regenerator GX and absorbed in the auxiliary absorber AX isdecreased, the efficiency of the refrigerating machine rises. However,when the temperature of the cooling water is high, the concentration ofthe solution at the outlet of the auxiliary absorber increases, alsothere is no drop in the condensation temperature, so the heat sourcetemperature required in the regenerator becomes higher. When thetemperature of the cooling water drops, the solution concentration atthe outlet of the auxiliary absorber also drops and the condensationtemperature becomes lower, so that the heat source temperature requiredin the regenerator can be lowered. The flow rate of refrigerant vaporgenerated in the auxiliary regenerator GX and absorbed in the auxiliaryabsorber AX may also be controlled based on the cooling watertemperature or a physical quantity equivalent to the cooling watertemperature.

FIG. 10 is a schematic structural diagram showing the fifth embodimentas a modification of the structure in FIG. 9. The absorptionrefrigerating machine of the present embodiment includes a method forcontrolling the flow rate of the refrigerant vapor generated in theauxiliary regenerator GX and absorbed in the auxiliary absorber AX.

The present embodiment includes a heating rate control in the auxiliaryregenerator GX (heat source introduction rate control to GX by thethree-way valve VA at GX inlet in FIG. 10, or solution spray flow ratecontrol to GX by VB of FIG. 10), or an absorption performance control inthe auxiliary absorber AX (cooling water flow rate control to AX by VCof FIG. 10, or solution spray flow rate control to AX by VD of FIG. 10).

In this figure, the valve VA is placed in the hot water pipe 81 in thesame manner as the three-way valve V1 described in the first embodiment.

The three-way valve VD is placed on the solution flow 1 b from thesolution pump SP to the auxiliary absorber AX. One port of the three-wayvalve VD is connected to the auxiliary absorber AX. The port of thethree-way valve VD may be connected to the suction side of the solutionpump SP rather than the auxiliary absorber AX, or in other words, may beconnected to the solution flow path 2 a or the solution flow path 1 a.

The three-way valve VC is disposed on the outlet side of the auxiliaryabsorber AX in the cooling water pipe. The three-way valve VC may bedisposed on the inlet side of the auxiliary absorber AX in the coolingwater pipe.

The three-way valve VB is placed on the solution flow path 3 connectingthe high-temperature heat exchanger XH and the auxiliary regenerator GX.One port of the three-way valve VB connects to the solution flow path 4connecting the auxiliary regenerator GX and the low-temperature heatexchanger XL.

In the present embodiment, when the amount of refrigerant vaporgenerated in the auxiliary regenerator GX and absorbed in the auxiliaryabsorber AX is reduced, the heat source quantity required by theauxiliary regenerator GX becomes small and the required temperature alsodecreases. However, the heat source temperature required by theregenerator G remains high. The heat source substance is preferablysupplied first of all to the regenerator G, and next supplied to theauxiliary regenerator GX. In other words, a high heat source temperaturecan be utilized on the regenerator G side so the efficiency can beeasily raised.

When the amount of refrigerant vapor generated in the auxiliaryregenerator GX and absorbed in the auxiliary absorber AX is increased,the heat source quantity becomes large, and the temperature at the heatsource outlet drops. However, when the amount of refrigerant vapor isdecreased, the heat source quantity becomes small, and the temperatureat the heat source outlet rises. In such cases, control is preferablyperformed by control valves by setting the heat source temperature (heatsource outlet temperature) to a target value to control the refrigerantvapor generated in the auxiliary regenerator GX and absorbed in theauxiliary absorber AX.

While the heat source is circulating in the absorption refrigeratingmachine and the heat source point when the heat source outlettemperature drops, the temperature also drops at the heat source inletso that a target value may be set for the heat source inlet rather thanthe heat source outlet, and a position for detecting the heat sourcetemperature need not be specified. The target is generally the heatsource outlet temperature or the heat source inlet temperature.

FIG. 12 is a schematic structural diagram showing the absorptionrefrigerating machine of the sixth embodiment of this invention. Thepresent embodiment is a modified example of the fourth embodiment.

As shown in FIG. 12, the differential between the cold water inlet andoutlet temperatures is utilized in the same manner as in the secondembodiment, and in order to further raise efficiency, the absorber A ofthe absorption refrigerating machine is subdivided into a low-pressureabsorber AL and a high-pressure absorber AH, and the evaporator E issubdivided into a low-pressure evaporator EL and a high-pressureevaporator EH. The cold water is first of all supplied to thehigh-pressure evaporator EH, and the cooled cold water next is suppliedto the low-pressure evaporator EL, and the concentrated solution fromthe auxiliary regenerator GX is first of all supplied to thelow-pressure absorber AL, the refrigerant vapor from the low-pressureevaporator EL is absorbed, and the solution, after absorbing therefrigerant vapor in the low-pressure absorber AL, is supplied to thehigh-pressure absorber AH, and the refrigerant vapor from thehigh-pressure evaporator EH is absorbed.

FIG. 13 is a Dühring diagram of the solution cycle with respect to FIG.12. As shown in the diagram, the saturation temperature of thehigh-pressure evaporator EH rises, and the concentration of the dilutedsolution leaving the high-pressure absorber AH lowers. The flow raterequired for lowering further the concentration in the auxiliaryabsorber AX can in this way be reduced, and the efficiency can beincreased compared to the case of FIG. 9.

A method for flowing cooling water, where the path branches at thecooling water inlet, and one branch flows from the condenser to theabsorber, while the other branch flows to the auxiliary absorber, ispreferable because the required hot water temperature is low.

In the absorption refrigerating machine of the embodiment of the presentinvention as described above, the absorption refrigerating machineincludes a regenerator, a condenser, an absorber, an evaporator, anauxiliary regenerator and auxiliary absorber, heats the concentratedsolution from the regenerator in the auxiliary regenerator, generatesrefrigerant vapor, and further concentrates the solution, and whilecooling the diluted solution from the absorber in the auxiliaryabsorber, absorbs the refrigerant vapor from the auxiliary regenerator,and includes a low-temperature heat exchanger for performing heatexchange between the concentrated solution supplied from the auxiliaryregenerator to the absorber and the diluted solution supplied from theauxiliary absorber to the regenerator, and includes a high-temperatureheat exchanger for heating the diluted solution leaving from thelow-temperature heat exchanger and sent to the regenerator, with theconcentrated solution supplied from the regenerator to the auxiliaryregenerator.

The absorption refrigerating machine may be constructed such that theabsorber is subdivided into a low-pressure absorber and a high-pressureabsorber, the evaporator is subdivided into a low-pressure evaporatorand high-pressure evaporator, the cold water is first of all supplied tothe high-pressure evaporator, and the cooled cold water is next suppliedto the low-pressure evaporator, the concentrated solution from theauxiliary regenerator is first of all supplied to the low-pressureabsorber, the refrigerant vapor from the low-pressure evaporator isabsorbed, and the solution, after absorbing the refrigerant vapor in thelow-pressure absorber, is supplied to the high-pressure absorber, therefrigerant vapor from the high-pressure absorber is absorbed, and thediluted solution is supplied to the auxiliary absorber.

An absorption refrigerating machine according to another embodiment ofthe present invention, may include a regenerator, a condenser, anabsorber, an evaporator, an auxiliary regenerator and auxiliaryabsorber, and may be constructed such that the concentrated solutionfrom the regenerator is heated in the auxiliary regenerator to generaterefrigerant vapor and further concentrates the solution, and whilecooling the diluted solution from the absorber in the auxiliaryabsorber, the refrigerant vapor from the auxiliary regenerator isabsorbed, and the heat transfer area of the auxiliary regenerator may beequal to or smaller than one-third of the heat transfer area of theregenerator, and the heat transfer area of the auxiliary absorber may beequal to or smaller than two-thirds of the heat transfer area of theabsorber.

These absorption refrigerating machines may be constructed so that theheat source substance is supplied first of all to the regenerator, andnext supplied to the auxiliary regenerator.

An absorption refrigerating machine according to another embodiment ofthe present invention, may include a regenerator, a condenser, anabsorber, an evaporator, an auxiliary regenerator and auxiliaryabsorber, and may have a circulating path for the absorption solutionfrom the absorber to the auxiliary absorber, to the regenerator, to theauxiliary regenerator, and to the absorber, and may be provided withmeans for controlling the heat transfer performance of the auxiliaryregenerator and/or means for controlling the heat transfer performanceof the auxiliary absorber.

An absorption refrigerating machine may be constructed such that theabsorber is subdivided into a low-pressure absorber and a high-pressureabsorber, and the evaporator is subdivided into a low-pressureevaporator and high-pressure evaporator, the cold water is first of allsupplied to the high-pressure evaporator, and the cooled cold water isnext supplied to the low-pressure evaporator, the concentrated solutionfrom the regenerator and the auxiliary regenerator is first of allsupplied to the low-pressure absorber, the refrigerant vapor from thelow-pressure evaporator is absorbed, and the solution, after absorbingthe refrigerant vapor in the low-pressure absorber, is supplied to thehigh-pressure absorber, the refrigerant vapor from the high-pressureabsorber is absorbed, and the diluted solution is supplied to theauxiliary regenerator. A structure of this type can increase theefficiency of the absorption refrigerating machine even further.

The means for controlling the heat transfer performance of the auxiliaryregenerator may be a hot water flow rate control valve for controllingthe flow rate of the hot water bypassing and/or passing through theauxiliary regenerator, or a solution flow rate control valve forcontrolling the flow rate of the solution bypassing and/or passingthrough the heat transfer section of the auxiliary regenerator.

The means for controlling the heat transfer performance of the auxiliaryabsorber may be a cooling water flow rate control valve for controllingthe flow rate of cooling water bypassing and/or passing through theauxiliary absorber, or a solution flow rate control valve forcontrolling the flow rate of the solution bypassing and/or passingthrough the heat transfer section of the auxiliary absorber.

The means for controlling the heat transfer performance of the auxiliaryregenerator and/or the means for controlling the heat transferperformance of the auxiliary absorber may include a control mechanismfor making control based on the temperature of the hot water functioningas the heat source or the temperature of the solution in theregenerator.

An absorption refrigerating machine according to yet another embodimentof the present invention, includes a regenerator, a condenser, anabsorber, an evaporator, an auxiliary regenerator and auxiliaryabsorber, and is constructed such that the concentrated solution fromthe regenerator is heated in the auxiliary regenerator and generatesrefrigerant vapor and is further condensed, and the generatedrefrigerant vapor is absorbed in the auxiliary absorber while cooling byutilizing a portion of the diluted solution mixture made up of thediluted solution of the absorber outlet and the diluted solution of theauxiliary absorber outlet, and includes a path to send the remainder ofthe diluted solution mixture to the regenerator, and a low-temperatureheat exchanger for heating the diluted solution mixture sequentially onthe path with the concentrated solution supplied from the auxiliaryregenerator to the absorber, and a high-temperature heat exchanger forheating the diluted solution mixture leaving from the low-temperatureheat exchanger and sent to the regenerator, with the concentratedsolution supplied from the regenerator to the auxiliary regenerator.

The absorption refrigerating machine may be constructed such that, toutilize the difference between the cold water inlet and outlettemperatures to further raise efficiency, the absorber of the absorptionrefrigerating machine is subdivided into a low-pressure absorber and ahigh-pressure absorber, and the evaporator is subdivided into alow-pressure evaporator and a high-pressure evaporator, and the coldwater is first of all supplied to the high-pressure evaporator, and thecooled cold water is next supplied to the low-pressure evaporator, theconcentrated solution from the regenerator is first of all supplied tothe low-pressure absorber, the refrigerant vapor from the low-pressureevaporator is absorbed, and the solution, after absorbing therefrigerant vapor in the low-pressure absorber, is supplied to thehigh-pressure absorber, the refrigerant vapor from the high-pressureevaporator is absorbed, and the diluted solution, after absorbing therefrigerant vapor in the high-pressure absorber, is mixed with thediluted solution from the auxiliary absorber to form a diluted solutionmixture, and a portion of the diluted solution mixture is supplied tothe auxiliary absorber, and the remainder is supplied to theregenerator.

INDUSTRIAL APPLICABILITY

The present invention constructed as described above is an absorptionrefrigerating machine utilizing hot water of 60 to 70 degrees Celsius asa heat source, and although inferior to the single effect absorptionrefrigerating machine, provides better efficiency than thedouble-concentrating type absorption refrigerating machine, and can beeffectively utilized under open air conditions where the temperature ofthe cooling water has dropped, in other words the efficiency increasesas the cooling water temperature drops, and according to the temperatureconditions, can be operated with the same efficiency as the singleeffect type.

1. An absorption refrigerating machine comprising: a regeneratorgenerating refrigerant vapor and concentrating a solution; a condensercondensing the generated refrigerant vapor; an evaporator evaporatingthe condensed refrigerant; an absorber absorbing the evaporatedrefrigerant vapor into the solution; an auxiliary regenerator heatingthe concentrated solution from the regenerator, generating therefrigerant vapor and further concentrating the solution; an auxiliaryabsorber absorbing the refrigerant vapor generated in the auxiliaryregenerator while cooling a diluted solution from the absorber; alow-temperature heat exchanger performing heat exchange between theconcentrated solution sent from the auxiliary regenerator to theabsorber and the diluted solution sent from the auxiliary absorber tothe regenerator; a high-temperature heat exchanger heating the dilutedsolution leaving the low-temperature heat exchanger and sent to theregenerator with the concentrated solution sent from the regenerator tothe auxiliary regenerator.
 2. The absorption refrigerating machineaccording to claim 1, wherein the absorber is subdivided into alow-pressure absorber and a high-pressure absorber, the evaporator issubdivided into a low-pressure evaporator and a high-pressureevaporator, the cold water is first of all supplied to the high-pressureevaporator, the cooled cold water is next supplied to the low-pressureevaporator, the concentrated solution from the auxiliary regenerator isfirst of all supplied to the low-pressure absorber, the refrigerantvapor from the low-pressure evaporator is absorbed, the solution, afterabsorbing the refrigerant vapor in the low-pressure absorber is suppliedto the high-pressure absorber, the refrigerant vapor from thehigh-pressure evaporator is absorbed, and the diluted solution, afterabsorbing the refrigerant vapor, is supplied to the auxiliary absorber.3. The absorption refrigerating machine according to claim 1, whereinthe heat source substance for heating the solution is first of allsupplied to the regenerator, and then supplied to the auxiliaryregenerator.
 4. An absorption refrigerating machine comprising: aregenerator generating refrigerant vapor and concentrating a solution; acondenser condensing the generated refrigerant vapor; an evaporatorevaporating the condensed refrigerant; an absorber for absorbing theevaporated refrigerant vapor into the solution and; an auxiliaryregenerator heating the concentrated solution from the regenerator,generating the refrigerant vapor and further concentrating the solution;an auxiliary absorber absorbing the refrigerant vapor generated in theauxiliary regenerator while cooling a diluted solution from theabsorber, wherein a heat transfer area of the auxiliary regenerator isequal to or smaller than one-third of a heat transfer area of theregenerator, and a heat transfer area of the auxiliary absorber is equalto or smaller than two-thirds of a heat transfer area of the absorber.5. The absorption refrigerating machine according to claim 4, whereinthe absorber is subdivided into a low-pressure absorber and ahigh-pressure absorber, the evaporator is subdivided into a low-pressureevaporator and a high-pressure evaporator, the cold water is first ofall supplied to the high-pressure evaporator, the cooled cold water isnext supplied to the low-pressure evaporator, the concentrated solutionfrom the auxiliary regenerator is first of all supplied to thelow-pressure absorber, the refrigerant vapor from the low-pressureevaporator is absorbed, the solution, after absorbing the refrigerantvapor in the low-pressure absorber is supplied to the high-pressureabsorber, the refrigerant vapor from the high-pressure evaporator isabsorbed, and the diluted solution, after absorbing the refrigerantvapor, is supplied to the auxiliary absorber.
 6. The absorptionrefrigerating machine according to claim 4, wherein the heat sourcesubstance for heating the solution is first of all supplied to theregenerator, and then supplied to the auxiliary regenerator.
 7. Anabsorption refrigerating machine comprising: a regenerator generatingrefrigerant vapor and concentrating a solution; a condenser condensingthe generated refrigerant vapor; an evaporator evaporating the condensedrefrigerant; an absorber absorbing the evaporated refrigerant vapor intothe solution; an auxiliary regenerator for heating the concentratedsolution from the regenerator, generating the refrigerant vapor andfurther concentrating the solution; an auxiliary absorber absorbing therefrigerant vapor generated in the auxiliary regenerator while cooling adiluted solution from the absorber; a circulating path allowing thesolution to reach the absorber in sequence from the absorber, theauxiliary absorber, the regenerator, and the auxiliary regenerator; andat least one of means controlling heat transfer performance of theauxiliary regenerator and means controlling heat transfer performance ofthe auxiliary absorber.
 8. The absorption refrigerating machineaccording to claim 7, wherein the means for controlling the heattransfer performance of the auxiliary regenerator is a hot water flowrate control valve for controlling the flow rate of hot water bypassingand/or passing through the auxiliary regenerator, or a solution flowrate control valve for controlling the flow rate of solution bypassingand/or passing through a heat transfer section of the auxiliaryregenerator.
 9. The absorption refrigerating machine according to claim7, wherein the means for controlling the heat transfer performance ofthe auxiliary absorber is a cooling water flow rate control valve forcontrolling the flow rate of cooling water bypassing and/or passingthrough the auxiliary absorber, or a solution flow rate control valvefor controlling the flow rate of solution bypassing and/or passingthrough a heat transfer section of the auxiliary absorber.
 10. Theabsorption refrigerating machine according to claim 8, wherein the meansfor controlling the heat transfer performance of the auxiliary absorberis a cooling water flow rate control valve for controlling the flow rateof cooling water bypassing and/or passing through the auxiliaryabsorber, or a solution flow rate control valve for controlling the flowrate of solution bypassing and/or passing through a heat transfersection of the auxiliary absorber.
 11. The absorption refrigeratingmachine according to claim 7, wherein at least one of the means forcontrolling the heat transfer performance of the auxiliary regeneratorand the means for controlling the heat transfer performance of theauxiliary absorber includes a control mechanism for making control basedon the temperature of hot water functioning as a heat source or thetemperature of the solution in the regenerator.
 12. The absorptionrefrigerating machine according to claim 8, wherein at least one of themeans for controlling the heat transfer performance of the auxiliaryregenerator and the means for controlling the heat transfer performanceof the auxiliary absorber includes a control mechanism for makingadjustments based on the temperature of hot water functioning as a heatsource or the temperature of the solution in the regenerator.
 13. Theabsorption refrigerating machine according to claim 7, wherein theabsorber is subdivided into a low-pressure absorber and a high-pressureabsorber, the evaporator is subdivided into a low-pressure evaporatorand a high-pressure evaporator, the cold water is first of all suppliedto the high-pressure evaporator, the cooled cold water is next suppliedto the low-pressure evaporator, the concentrated solution from theauxiliary regenerator is first of all supplied to the low-pressureabsorber, the refrigerant vapor from the low-pressure evaporator isabsorbed, the solution, after absorbing the refrigerant vapor in thelow-pressure absorber is supplied to the high-pressure absorber, therefrigerant vapor from the high-pressure evaporator is absorbed, and thediluted solution, after absorbing the refrigerant vapor, is supplied tothe auxiliary absorber.
 14. The absorption refrigerating machineaccording to claim 7, wherein the heat source substance for heating thesolution is first of all supplied to the regenerator, and then suppliedto the auxiliary regenerator.
 15. An absorption refrigerating machinecomprising: a regenerator generating refrigerant vapor and concentratinga solution; an evaporator evaporating a refrigerant; an absorberabsorbing the evaporated refrigerant vapor into the solution; anauxiliary regenerator heating the concentrated solution from theregenerator, generating the refrigerant vapor and further concentratingthe solution; an auxiliary absorber absorbing the refrigerant vaporgenerated in the auxiliary regenerator while cooling a diluted solutionfrom the absorber; a heat exchanger heating the diluted solution sentfrom the auxiliary absorber to the regenerator with the concentratedsolution sent from the regenerator to the auxiliary regenerator.